This section provides background information related to the present disclosure which is not necessarily prior art.
In view of increased consumer demand for motor vehicles equipped with advanced comfort and convenience features, many modern motor vehicles are now provided with keyless passive entry systems to permit locking and release of closure panels (i.e., doors, tailgates, liftgates and decklids) without use of a traditional key-type entry system. In this regard, popular features now available with many vehicle closure latch systems include power locking/unlocking and power release functionality. These “powered” features are typically provided by a closure latch assembly mounted to the closure panel and which includes a ratchet and pawl type of latch mechanism controlled via at least one electric actuator. In operation, the closure panel is latched in a closed position by virtue of a ratchet being positioned in a striker capture position to releaseably retain a striker that is mounted to a structural portion of the vehicle. The ratchet is held in its striker capture position by a pawl engaging the ratchet, when the pawl is located in a ratchet holding position. The closure latch assembly is operated in a “latched” mode when the pawl is located in its ratchet holding position. To release the closure panel from its closed position, the electric actuator is actuated to move the pawl from its ratchet holding position into a ratchet releasing position, whereby a ratchet biasing arrangement forcibly pivots the ratchet from its striker capture position into a striker release position so as to release the striker. The closure latch assembly is operating in an “unlatched” mode when the pawl is located in its ratchet releasing position. As an alternative to such single ratchet/pawl latch mechanisms, it is also known to employ a double ratchet/pawl type of latch mechanism within the closure latch assembly to reduce the release effort required for the electric actuator to release the latch mechanism during a power release operation.
To ensure that precipitation and road debris do not enter the vehicle, vehicle closure panels are equipped with weather seals around their peripheral edge and which are configured to seal against a mating surface of the vehicle body surrounding the closure opening. These weather seals also function to reduce wind noise. The weather seals are typically made from an elastomeric material and are configured to compress upon closing and latching of the closure panel by virtue of the closure latch assembly. As is recognized, increasing the compressive clamping force applied to the weather seals provides improved noise reduction within the passenger compartment. However, with the weather seals held in a highly compressed condition, they tend to force the closure panel toward its open position and this “opening” force is resisted by the latch mechanism of the closure latch assembly. Because the seal loads exerted on the latch mechanism are increased, the forces required to release the latch mechanism are also increased which, in turn, impacts the size and power requirements of the electric actuator. Further, an audible “pop-off” sound is sometimes generated following actuation of the electric actuator during the power release operation due to the quick release of the seal loads as the striker engages the ratchet of the latch mechanism as the ratchet is driven toward its striker release position.
To address this dichotomy between high seal loads and low release efforts, it is known to provide an arrangement for controllably releasing the seal loading in coordination with release of the latch mechanism. For example, European Publication No. EP1176273 discloses a single ratchet/double pawl type of power-operated latch mechanism that is configured to provide a progressive releasing of the ratchet for reducing noise associated with its release. In addition, European Publication EP0978609 utilizes an eccentric mechanism in association with a single ratchet/pawl type of latch mechanism to reduce seal loads prior to release of the ratchet.
While current closure latch assemblies are sufficient to meet regulatory requirements and provide enhanced comfort and convenience, a need still exists to advance the technology and provide alternative closure latch assemblies and arrangements that address and overcome at least some of the known shortcomings, particularly elimination of pop-off noise.